Cubic zirconia (ZrO2) is considered to be a suitable refractory host (Tm≈3000 K) for actinide confinement used for transmutation or high-temperature reactor projects. Literature data on radiation damage of this material are rather limited concerning studies with heavy ions [1]. Moreover, point defects were investigated only in the case of pure e...

Cubic zirconia (ZrO2) is considered to be a suitable refractory host (Tm≈3000 K) for actinide confinement used for transmutation or high-temperature reactor projects. Literature data on radiation damage of this material are rather limited concerning studies with heavy ions [1]. Moreover, point defects were investigated only in the case of pure electronic excitations with photons [2]. This study is focusing on defect creation in cubicstabilized zirconia exposed to energetic heavy ions, in particular on the characterization of defects and the role of the irradiation temperature on the damage process. Zirconia single-crystals stabilized by yttrium in the cubic fluorite structure (ZrO2: Y, with 9.5 mol % Y2O3) were used. Samples with <100> orientation were exposed to ions with energy of 11.4 MeV amu-1 (1.44-GeV 132 Xe Minimize

Cubic zirconia (ZrO2) is considered to be a suitable refractory host (Tm∼3000 K) for actinide confinement used for transmutation or high-temperature reactor projects. Literature data on radiation damage of this material are rather limited concerning studies with heavy ions [1]. Moreover, point defects were investigated only in the case of pure e...

Cubic zirconia (ZrO2) is considered to be a suitable refractory host (Tm∼3000 K) for actinide confinement used for transmutation or high-temperature reactor projects. Literature data on radiation damage of this material are rather limited concerning studies with heavy ions [1]. Moreover, point defects were investigated only in the case of pure electronic excitations with photons [2]. This study is focusing on defect creation in zirconia exposed to energetic charged particles, in particular on the characterization of defects and the analysis of the respective roles of elastic collisions and electronic excitations in the damage processes. We also investigated beam-induced volume changes (swelling), which is an important issue for nuclear applications of this material. Zirconia single crystals stabilized by yttrium in the cubic fluorite structure (ZrO2: Y, with 9.5 mol % Y2O3) were used as received (AR) or reduced by vacuum-annealing (R). Samples with <100> and <110> orientation were exposed to electrons (1-2.5-MeV) as well as to a large variety of different energetic ions (73-MeV 52 Cr and 2.6- Minimize

A simple model for the nucleation and growth of single wall carbon nanotubes from a graphene sheet at the surface of a metallic catalyst saturated in carbon is developed. It enables to predict the geometry and energy of tube embryos of all possible chiralities, as well as the way that they can grow. It is shown that armchair-like chiralities are...

Via a direct coupling between the magnetic order parameter and the singlet Josephson supercurrent, we detect spin-wave resonances, and their dispersion, in ferromagnetic Josephson junctions in which the usual insulating or metallic barrier is replaced with a weak ferromagnet. The coupling arises within the Fraunhofer interferential description o...

Via a direct coupling between the magnetic order parameter and the singlet Josephson supercurrent, we detect spin-wave resonances, and their dispersion, in ferromagnetic Josephson junctions in which the usual insulating or metallic barrier is replaced with a weak ferromagnet. The coupling arises within the Fraunhofer interferential description of the Josephson effect, because the magnetic layer acts as a time dependent phase plate. A spin-wave resonance at a frequency ws implies a dissipation that is reflected as a depression in the current-voltage curve of the Josephson junction when hbar ws = 2eV. We have thereby performed a resonance experiment on only 10^7 Ni atoms. ; Comment: 4 pages, 4 figures Minimize

The first measurements of an upper bound for the low-field conductivity of a molecular wire are presented here. We were able to encapsulate polypyrrole with chain lengths more than 10 monomers within the channels of different zeolites. Although the chains are fully oxidized by intrazeolite Fe3 + ions, and should conduct (when included in a bulk ...

The first measurements of an upper bound for the low-field conductivity of a molecular wire are presented here. We were able to encapsulate polypyrrole with chain lengths more than 10 monomers within the channels of different zeolites. Although the chains are fully oxidized by intrazeolite Fe3 + ions, and should conduct (when included in a bulk polymer), they do not exhibit, in the zeolite, significant ac conductivity up to 1 GHz. This suggests that other strategies than low field conductivity are needed to inject charges and transmit information through isolated molecular wires. Minimize

The elastic diffuse neutron scattering of a TiN0.82 single crystal has been measured in thermodynamic equilibrium at 700, 800 and 900 °C. The diffuse intensity is maximum at the (1/2 1/2 1/2) type reciprocal lattice positions. Nitrogen vacancies are found to situate preferentially as third neighbours on the metalloid f.c.c. sublattice. Pair inte...

The elastic diffuse neutron scattering of a TiN0.82 single crystal has been measured in thermodynamic equilibrium at 700, 800 and 900 °C. The diffuse intensity is maximum at the (1/2 1/2 1/2) type reciprocal lattice positions. Nitrogen vacancies are found to situate preferentially as third neighbours on the metalloid f.c.c. sublattice. Pair interaction ordering energies were calculated by mean-field approximation, Monte-Carlo simulations, and Cluster Variation Method ; the last two methods give very similar temperature independent pair energies : V1 ≃ 82 and V 2 ≃ 62 meV for first and second nitrogen neighbours respectively ; V3 and further interaction energies are very small. Titanium atoms are found to relax away, and nitrogen atoms to relax toward their first neighbour vacancies, by respectively 0.042 and 0.024 A. Minimize

The structure of two borosilicate glasses and melts has been investigated by neutron diffraction coupled with Reverse Monte Carlo (RMC) simulation. For both compositions (10B2O3 ⋅ 30Na2O ⋅ 60SiO2 and 10B2O3 ⋅ 15Na2O ⋅ 15CaO ⋅ 60SiO2), the fraction of tetrahedral boron ([4]B) drops from 0.7 to 0.3 from the glass to the melt. The change from a mod...

The structure of two borosilicate glasses and melts has been investigated by neutron diffraction coupled with Reverse Monte Carlo (RMC) simulation. For both compositions (10B2O3 ⋅ 30Na2O ⋅ 60SiO2 and 10B2O3 ⋅ 15Na2O ⋅ 15CaO ⋅ 60SiO2), the fraction of tetrahedral boron ([4]B) drops from 0.7 to 0.3 from the glass to the melt. The change from a modifying to a charge compensating role of cations during quench is related to the boron coordination change. These molecular scalemodifications explain the low viscosity of alkali/alkaline-earth borosilicate melts relative to alkali/alkaline-earth silicate melts, as the viscous flow is enhanced with the proportion of [3]B. RMC simulations of soda borosilicate glass and melt show a preferential interbonding between B and Si polyhedra. Such medium range order interbonding is unfavored in the soda-lime borosilicate glass showing a nearly random network. The effect of Ca enhancing the proportion of B-B pairs is here highlighted. Minimize